This invention relates to a method of managing power of a computer system which includes a plurality of computers, and more specifically, to a method of managing power in a computer system such as a super computer, which includes a large number of computers.
There has been known a technology of constructing a computer system which includes several hundreds to several thousands of nodes (computers) including a processor, which are coupled via a high-speed network. The computer system has been implemented as a cluster computer, a massively parallel computer, or a super computer.
In a computer system which includes several hundreds or several thousands of nodes as described above (parallel computer or cluster computer), power consumption per unit time of the computer system as a whole increases to an enormous amount even when power consumption of each node is several hundred W/h, and therefore it is costly to maintain a large-scale computer in terms of power charge.
Meanwhile, the above-mentioned large-scale computer is not always performing jobs on all the nodes for 24 hours a day, every day in every year. For example, there may be a case where a usage rate of the nodes, which is 100% during the daytime, drops to about 30% during the nighttime, or the usage rate of the nodes even during the daytime may further drop during the summer vacation. It is rare that a system constantly operates at the usage rate of 100% even in the case of a computer system with high usage rate. An average of the usage rate in a typical computer system is from 70% to 90%.
In a computer (node) that is executing no job, a processor or the like is brought to an idle state. There has been known a cluster computer, in which, when the idle state is detected in a processor of its own node, a predetermined command is issued to change the idle state to a suspended state (halting state), to thereby suppress wasteful power consumption (see, for example, JP 2003-162515 A).